My dissertation research focuses on answering questions regarding the osmoregulatory system in bony fishes, that is, the set of physiological mechanisms by which water and ion homoestasis is maintained. Specifically, I am investigating the evolution of the osmoregulatory system using an anadromous clupeid fish known as the alewife (Alosa pseudoharengus) <br/>

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My dissertation research focuses on answering questions regarding the osmoregulatory system in bony fishes, that is, the set of physiological mechanisms by which water and ion homoestasis is maintained. Specifically, I am investigating the evolution of the osmoregulatory system using an anadromous clupeid fish known as the alewife (Alosa pseudoharengus). <br/>

The reason I have chosen to study alewives is because of their interesting life history. Alewives are ancestrally anadromous - adults inhabit the open ocean and return yearly to small, freshwater systems to spawn. As members of the family Clupeidae, alewives are of a ancestrally and predominantly marine family. In Connecticut, multiple populations of alewife have been independently restricted to freshwater year-round - a phenomenon known as land-locking. Land-locking in alewives provides a unique opportunity to investigate the specific physiological and molecular adaptations made by fish when they transition from living in seawater to specializing in freshwater - environments that require drastically different methods of osmoregulating. Not only does this represent a significant gap in our knowledge of osmoregulatory physiology, but changes to this system that permitted organisms to specialize in freshwater represent major evolutionary transitions. Furthermore, the ecological transition from seawater to freshwater has been important in the creation of diversity among fishes, yet we know little about the adaptations that facilitate such transitions. <br/>

The reason I have chosen to study alewives is because of their interesting life history. Alewives are ancestrally anadromous - adults inhabit the open ocean and return yearly to small, freshwater systems to spawn. As members of the family Clupeidae, alewives are of a ancestrally and predominantly marine family. In Connecticut, multiple populations of alewife have been independently restricted to freshwater year-round - a phenomenon known as land-locking. Land-locking in alewives provides a unique opportunity to investigate the specific physiological and molecular adaptations made by fish when they transition from living in seawater to specializing in freshwater - environments that require drastically different methods of osmoregulating. Not only does this represent a significant gap in our knowledge of osmoregulatory physiology, but changes to this system that permitted organisms to specialize in freshwater represent major evolutionary transitions. Furthermore, the ecological transition from seawater to freshwater has been important in the creation of diversity among fishes, yet we know little about the adaptations that facilitate such transitions. <br/>

Dissertation Research

My dissertation research focuses on answering questions regarding the osmoregulatory system in bony fishes, that is, the set of physiological mechanisms by which water and ion homoestasis is maintained. Specifically, I am investigating the evolution of the osmoregulatory system using an anadromous clupeid fish known as the alewife (Alosa pseudoharengus).

The reason I have chosen to study alewives is because of their interesting life history. Alewives are ancestrally anadromous - adults inhabit the open ocean and return yearly to small, freshwater systems to spawn. As members of the family Clupeidae, alewives are of a ancestrally and predominantly marine family. In Connecticut, multiple populations of alewife have been independently restricted to freshwater year-round - a phenomenon known as land-locking. Land-locking in alewives provides a unique opportunity to investigate the specific physiological and molecular adaptations made by fish when they transition from living in seawater to specializing in freshwater - environments that require drastically different methods of osmoregulating. Not only does this represent a significant gap in our knowledge of osmoregulatory physiology, but changes to this system that permitted organisms to specialize in freshwater represent major evolutionary transitions. Furthermore, the ecological transition from seawater to freshwater has been important in the creation of diversity among fishes, yet we know little about the adaptations that facilitate such transitions.

My research focuses mainly on the osmoregulatory processes of the gills, since gills are the main site of ion exchange in fish. I explore how survival, plasma osmolality, NKA activity and gene expression at several candidate osmoregulatory loci differ between landlocked and anadromous alewives when challenged in a common salinity environment. Such experiments identify the physiological mechanisms that have diverged between landlocked and anadromous alewives. So far I have shown that landlocked alewives are less tolerant of seawater than anadromous alewives, and have less effective ion secretion mechanisms at the gill. These differences appear to be at least partially driven by changes in the expression of genes that code for ion transporters involved in ion secretion at the gill. Natural selection has likely acted to reduce osmoregulatory function in seawater among landlocked alewives, since it may bear constitutive energetic costs. My current work is aimed at understanding differences between independently evolved landlocked populations, and identifying the genomic mechanisms that underlie differences in osmoregulatory function between the two population types.